1. Field of the Invention
This invention relates generally to methods for manufacturing filled resilient and pliable articles, and more particularly to a process for manufacturing double bladder resilient articles containing a mass of tiny glass spheres having the consistency and appearance of a fine powder with a thin layer of lubricating powder disposed between the plies of the resilient bladders.
2. Brief Description of the Prior Art
The present invention is directed toward an improved process for manufacturing filled double bladder resilient articles, such as therapeutic resilient hand exercisers and wrist supports of the type disclosed in my previous U.S. patent applications Ser. No. 08/678,660 and Ser. No. 08/911,295. My previous patent applications do not teach the improved process of forming the inner and outer bladders nor the process of forming a lubricating powder layer between the bladder surfaces which is the subject matter of the present invention.
There are several commercially available resilient hand exercise articles known in the art that are gripped in the palm of the hand and squeezed.
A resilient rubber hand exerciser known as the "Eggserciser".TM. is sold by Eggstra Enterprises, Inc., of Alabaster, Ala. This device is an egg-shaped member molded of homogeneous foam rubber.
Other hand exercisers are known which utilize a single or double layer resilient outer covering or bladder filled with sand, seed, grain, or other "granular" or crystalized particles which have flat surfaces and/or sharp points. However, the sharp surfaces or points of the "granular" or crystalized filler material will abrade the interior surface of the resilient bladder and cause premature wear resulting in short product life, and leakage of the filler material.
A pliable hand exerciser sold by Qualatex of Wichita, Kans. under the name "Ad Impressions".TM. ASI 78200 is a natural latex balloon filled with hard granular particles having the consistency of sand. The neck of the balloon is tied in a knot. This device has only a single layer of natural latex and the filler material particles are irregular shaped many faceted particles with flat surfaces and sharp edges and range in particle size from about 1/32" to about 3/64". The Qualatex device is firm and hard, has a "crunching" feel when squeezed, has very poor resiliency, and substantially retains a distorted shape after being squeezed.
Therapeutic hand exercisers known as the "Gripp".TM. and "Thera-Gripp".TM. are sold by Abilitations of Atlanta Ga. These devices resemble a small ball in their natural state and are filled with a material which appears to be yellow seeds or grain, similar to wheat or oats, permanently encased in two layers of natural latex. The filler material particles are oval-shaped with two flat sides, approx. 3/32" in length and 1/32" thick. These devices are relatively firm and hard, have a "crunching" feel when squeezed, and have poor resiliency.
Scatterday, U.S. Pat. No. 5,350,342 discloses a deformable semi-resilient grip having a bladder consisting of a single thick layer, a thin layer surrounded by a thick layer, or a number of thin layers wherein the layers are fixed together which is filled with a mixture of lubricating powder intermixed with filler particles. There is no suggestion of the desirability of providing a lubricating between the walls of the bladders to allow relative movement, instead, they are fixed together.
Tarnoff, U.S. Pat. No. 4,952,190 discloses a deformable novelty toy having a single layer bladder containing a cohesive mixture of low-density microspheres and a small amount of liquid, such as water, mineral oils, glycols, etc., in an amount effective to unite the microspheres and provide cohesion and moldability. Thus, the filler material mixture has a high resistance to relative movement such that the article is capable of absorbing impact energy by deformation, rather than being resilient. This article is provided with a single layer and there is no suggestion of providing double bladders that allow relative movement.
Wrist support devices for supporting the wrist of a person performing repetitive tasks with their wrist, hand and fingers, such as using a computer mouse and typing on a keyboard are also known in the art.
There are several commercially available wrist support devices which consist of a pad formed of neoprene or homogeneous foam rubber that may be attached to a computer mouse or keyboard. These types of wrist supports are relatively stiff and non-compliant to the user's wrist. Other wrist support devices are known which utilize an outer covering or bladder filled with a gel, or with seed, grain, or other "granular" or crystalized particles which have flat surfaces and/or sharp points.
Garcia et al, U.S. Pat. No. 5,228,655 discloses a wrist rest support which includes a base pad that is positioned partially under the keyboard or mouse and a section extending away therefrom that has a top surface for supporting the wrists. In one embodiment the device has detachable foam riser sections which can be substituted to change the height of the wrist supporting section.
Prokop, U.S. Pat. No. 5,566,913 discloses a wrist rest article which can also be squeezed in the hands as an exercise means. This article has an elastic inner envelope formed of a sheet of latex rubber with an outer covering made of Spandex.TM. I. E. DuPont Company, or other fabric blends. The article is filled with a gelatinous material that supports the wrist and may also be heated or cooled to provide additional therapeutic effects.
Hart, U.S. Pat. No. 5,445,349 discloses a wrist support article made of a flexible tubular cloth container which is filled with particulate material such as rice. The article provides a stable support for the wrist and gently massages the wrist during finger movement, and may also be heated or cooled to provide additional therapeutic effects.
Fuller, U.S. Pat. No. 5,158,255 discloses a generally cylindrical wrist rest article that provides a support for the wrist and can also be grasped and squeezed to function as an exercise means. This article has a tubular solid rigid core that cannot bend surrounded by a yieldable foam layer having an irregular exterior and a soft fabric outer covering.
The prior art articles of the type that are made with a single layer of resilient latex are particularly non-resiliently responsive and tend to be only pliable, rather than resilient, and substantially retain the distorted configuration after being squeezed.
The prior art articles that are formed with a single or double layer resilient bladder filled with sand, seed, grain, or other "granular" or crystalized particles which have flat surfaces and/or sharp points. The sharp surfaces or points of the "granular" or crystalized filler material will abrade the interior surface of the resilient bladder and cause premature wear resulting in short product life, and leakage of the filler material.
The prior art articles of the type that are filled with irregular shaped materials or particles having facets or flat surfaces are uncomfortable to the hand and wrist, are relatively hard, and do not provide a smooth rolling action during wrist movement. If they also function as an exerciser when squeezed, they produce a "crunching" action due to the relative movement between the irregular shaped particle surfaces as they are compressed and displaced and this type of filler material makes them harder to squeeze, or more resistant to squeezing. Whether functioning as a wrist support or exerciser, these types of articles tend to hold their distorted shape for a period of time until the resiliency of the bladder forces the irregular shaped particles to move relative to one another as the device slowly resumes its natural shape. Thus, they are relatively non-resiliently responsive and tend to be only pliable, rather than resilient.
The prior art articles that are formed with a single or double layer resilient bladder filled with sand, seed, grain, or other "granular" or crystalized particles which have flat surfaces and/or sharp points are also prone to premature wear resulting in short product life, and leakage of the filler material due to the sharp surfaces or points of the "granular" or crystalized filler material abrading the interior surface of the resilient bladder.
The present invention is distinguished over the prior art in general, and these patents in particular, by a process for manufacturing double bladder resilient articles containing a mass of tiny glass spheres having the consistency and appearance of a fine powder. The present process provides a layer of lubricating powder disposed between the exterior surface of the inner bladder and interior surface of the outer bladder which prevents the bladder surfaces from sticking together and allows relative sliding movement therebetween. The present process fills the double bladder units with tiny spheres that roll on each other upon squeezing and releasing pressure on the article, thus, the resulting article has very low resistance to relative movement of the particles and allows the article to be compressed quickly and to resume its natural shape quickly due to the resiliency of the superposed bladders and the lubricating powder disposed between the plys, and thereby produces a smooth squishy sensation.